Star crust 10 billion times stronger than steel, physicists find
May 6, 2009
ROSAT HRI image of Puppis A. Image: NASA.
(PhysOrg.com) -- Research by a theoretical physicist at Indiana University shows that the crusts of neutron stars are 10 billion times stronger than steel or any other of the earth's strongest metal alloys.
Charles Horowitz, a professor in the IU College of Arts and Sciences' Department of Physics, came to the conclusion after large-scale molecular dynamics computer simulations were conducted at Indiana University and Los Alamos National Laboratory in New Mexico. The research will appear Friday (May 8) in Physical Review Letters.
Exhibiting extreme gravity while rotating as fast as 700 times per second, neutron stars are massive stars that collapsed once their cores ceased nuclear fusion and energy production. The only things more dense are black holes, as a teaspoonful of neutron star matter would weigh about 100 million tons.
Scientists want to understand the structure of neutron stars, in part, because surface irregularities, or mountains, in the crust could radiate gravitational waves and in turn may create ripples in space-time. Understanding how high a mountain might become before collapsing from the neutron star's gravity, or estimating the crust's breaking strain, also has implications for better understanding star quakes or magnetar giant flares.
"We modeled a small region of the neutron star crust by following the individual motions of up to 12 million particles," Horowitz said of the work conducted through IU's Nuclear Theory Center in the Office of the Vice Provost for Research. "We then calculated how the crust deforms and eventually breaks under the extreme weight of a neutron star mountain."
Performed on a large computer cluster at Los Alamos National Laboratory and built upon smaller versions created on special-purpose molecular dynamics computer hardware at IU, the simulations identified a neutron star crust that far exceeded the strength of any material known on earth.
The crust could be so strong as to be able to elicit gravitational waves that could not only limit the spin periods of some stars, but that could also be detected by high-resolution telescopes called interferometers, the modeling found. An online version of the research paper, "The breaking strain of neutron star crust and gravitational waves," can be found at http://arxiv.org/PS_cache/arxiv/pdf/0904/0904.1986v1.pdf .
"The maximum possible size of these mountains depends on the breaking strain of the neutron star crust," Horowitz said. "The large breaking strain that we find should support mountains on rapidly rotating neutron stars large enough to efficiently radiate gravitational waves."
Because of the intense pressure found on neutron stars, structural flaws and impurities that weaken things like rocks and steel are less likely to strain the crystals that form during the nucleosynthesis that occurs to form neutron star crust. Squeezed together by gravitational force, the crust can withstand a breaking strain 10 billion times the pressure it would take to snap steel.
Provided by Indiana University (news : web)
Jul 11, 2007 |
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We can met with similar behavior at the case of boson condensates, which can be manipulated by external magentic field from outside, when they appear quite sticky, whereas from inside they're superconductive.
Every close sectarian community or society behaves by the same way: from outside it's heavilly censored and conservative against changes, whereas from inside it's totalitarian and ideas are spreading here without opposition.
A quite interesting stuff, isn't it?
Professor Charles Horowitz and PhysOrg readers may be interested in the rigid, iron-rich structures that the SOHO and TRACE spacecrafts observed in the Sun.
These are shown in Figure 1 (page 2) of a paper published in Physics of Atomic Nuclei 69, number 11, pp. 1847-1856 (Nov 2006); Yadernaya Fizika 69, number 11, (Nov 2006); PAC: 96.20.Dt DOI: 10.1134/S106377880611007X
http://arxiv.org/...609509v3
With kind regards,
Oliver K. Manuel
http://www.omatumr.com
electrons are assumed to play no significant role other
than screening of interactions between ions. In my option, at these densities, 10^13 g / cm^3 (that's ten thousand billion times more dense than water) this assumption is pretty ridiculous.
geez, we've known this since Larry Niven's "Neutron Star" (Oct '66) and episode 35 of Star Trek's "The Doomsday Machine" (Oct '67) written by Norman Spinrad.
This neutronium has some extreme properties. I wonder if neutrinos can pass through it.
i take it this is the weight of the matter on the star and not on earth ?
what i mean to say is, its strength is due to the extreme gravity and not because its a special kind of matter or anything ?
sorry if i sound stupid but i dont know much about physics..
Or is it shown somewhere that space-time can be infinitely twisted and stretched out in the spherical region around black holes, neutron stars, quasars etc?
Bear in mind my field is computer science / quantum cryptography so i am out of my lane here...
But every sufficiently tiny droplet of such dense matter exhibits a extreme surface tension, which increases the hydrostatic pressure inside of droplets of neutrons in such a way, the neutrons are stabilized here in the same way, like inside of neutron stars. Note that such mechanism works only when the surface curvature remains sufficiently high, i.e. when droplet isn't large then common atom nuclei.
Such droplet stabilized by surface tension is called a strangelet. The strangelets composed of pure neutron fluid aren't completely stable and they decompose fast into protons and electrons. But by adding of excessive protons in 1:1 ration the decomposition can be prohibited in such a way, the resulting droplets remains stable. We are calling them an atom nuclei. The danger of strangelet formation is, they have a tendency to expel protons from atom nuclei, thus changing them into another strangelets composed of free neutrons. If the formation of new strangelets occurs faster, then surface decomposition of them, an avalanche reaction may occur, during which whole Earth would be transformed into giant exploding cluster of myriads tiny neutron stars.
The similar stabilization could be observed for every neutral particle, like the Xi or Lambda baryons or neutral mesons such as pions and kaons. As an observational evidence for neutronium strangelets can serve observation of tetraneutron state, as an evidence of more lightweight strangelets can serve the observation of pentaquark, quarkonium and gluonium states and mysterious dimuon decays, observed at Tevatron recently.
i wonder if that even made sense -- or addressed the question
http://www.aether...crit.gif
If yes, then the density fluctuations forming vaccum appear quite similar.
http://superstrun...hole.gif
By contemporary understanding, here's no sharp boundary between neutron stars, quark stars and black holes, which I personally consider as a ultradense neutrino stars, rather then true singularities.
I would however, say that there is a sharp line between fantasy objects and real matter.
http://adsabs.har...h..7155G
In addition to black holes, some contemporary scientists are believing in preon stars, quark stars, dark energy stars, fuzzballs, quarkonium stars, gravastars, white holes and many other objects.
It does. The phenomenon is called frame dragging. Even the rotation of the Earth, drags space-time along with it.
As with much else, frame dragging falls out of Einstein's math and can be tested and measured. And has been.
"In addition to black holes, some contemporary scientists are believing in preon stars, quark stars, dark energy stars, fuzzballs, quarkonium stars, gravastars, white holes and many other objects."
Yes. And a Boojun is a particularly viscous type of Snark.
I think that is the weight of the matter on Earth. The matter in a neutron star is almost entirely neutrons. This "neutron matter" has a density similar to that of an atomic nucleus. So, in short, it is a special kind of matter and the large number given is due to this matter's extremely high density.
If you introduce an omnidirectional space-time expansion, it changes the shear motion a bit with distance and you'll get the dark matter phenomena - that's all that simple.
http://www.space....ive.html
"Star Trek's Warp Drive: Not Impossible"
http://en.wikiped.../EmDrive
http://en.wikiped...d_effect
I suspect that it'd be pretty warm in the general vicinity of your teaspoon of neutron star material too - you'd need a teaspoon with a very, very, very high melting point. ;)
but seriously could someone answer the question?
Wouldn't it be busy expanding into something the size of a mountain? ;P
If I remember correctly, there was a report within the past several months that indicated a star with a very high mass (~1.6 solar masses?) had been discovered. There was speculation that this might be a "quark star." However, as far as I know, the equation of state of matter is not known very well for such high densities (temperatures and pressures.) So, while a sufficiently massive stellar remnant will collapse into a black hole, and a somewhat less massive one (.8?<